A sheet of plasterboard is a sheet made of a layer of plaster covered, on at least one face, by a sheet of cardboard or of paper. Generally, the two faces of the sheet are covered by a sheet of cardboard or of paper.
The sheets of plasterboard are generally manufactured in a factory, and are used to make partitions, ceilings, to line rough walls, etc. These sheets therefore replace the use of powder plaster dissolved in water in order to coat walls, which is a tiring and lengthy operation and which requires significant know-how to obtain an optimum composition of the plaster and a satisfactory flatness of the coated surface.
These sheets have the advantage of being easy to manipulate and of allowing for rapid work. Furthermore, less know-how is needed to position them compared to traditional plaster. Finally, the factory production makes it possible to obtain plasters of optimal composition. However, for cost and management issues, the factory production entails producing sheets of standard sizes.
Although there are different standard dimensions, in length and in width and in thickness, it is often necessary to cut these sheets to adapt them to the widths and lengths of the walls or of the ceiling of the room in which they are to be installed.
This cutting, done on the work site to the ideal dimensions, has to be rapid and as clean as possible to allow for two sheets to be easily positioned contiguously.
Then, a finishing has to be carried out by filling the interstice between two contiguous sheets of plaster, using a filler product such as plaster or ready-to-use coating. Once applied, this filling product is smoothed using the coating knife.
The finishing step has to be as rapid as possible. For this, the number of gestures required of the user has to be limited. A clean cutting of the sheets would make it possible not only to limit the quantity of filler product used, but also the number of gestures to be made to smooth the surface on and in the vicinity of the interstice.
There are a number of solutions for cutting a sheet of plasterboard.
The most widely used consists in “marking” the sheet with a cutter blade (a cutter blade, known from the prior art and illustrated in FIG. 13, consists of a plate having a doubly beveled edge, that is to say that both faces of the plate are beveled).
This operation makes it possible to cut the first sheet of cardboard and score the layer of plaster. Then, the operator exerts a stress on the sheet so that the layer of plaster is broken into two parts along the score. Finally, the operator cuts the second sheet of cardboard with his cutter to free the two sheet parts. Generally, in this last step, the second sheet of paper is torn rather than cut, which creates an irregularity on the surface of the sheet of plasterboard that has to be filled in the finishing stage.
This solution is dangerous for the operator because of the use of the cutter. In practice, the scoring obtained is never rectilinear, even with the use of a guide, and it often happens that the speed of the scoring movement results in a sudden deviation of the blade of the cutter from the guide to the body of the user.
It is for this reason that some companies prohibit their workers from using this practice. Some public institutions even prohibit this practice in their calls for bids, but in practice it is the method most widely used.
Moreover, this solution also has two technical drawbacks. Firstly, the use of a blade of the cutter generates non-rectilinear scores so that the break along the surface of the sheet can take forms that are so irregular that a new sheet has to be used and cut. Secondly, the cutting edge, obtained after having broken the layer of plaster, is still very uneven, in that the cutting edge obtained has numerous protuberances, even with a user with long experience. It is then difficult to fit two contiguous sheets whose cutting edge is uneven. It is also necessary, during the finishing stages, to use a significant quantity of filler material to obtain a perfectly planar surface between the two consecutive sheets.
To overcome this problem, some operators have proposed a second cutting solution consisting in using a straight-back hand saw or a pad saw. The teeth of the blade of this saw has to be chosen with care to avoid plaster chips and generating an uneven cutting edge. For the same reason, the cutting speed and frequency must also be suitable, which requires significant know-how.
When well done, this second cutting solution makes it possible to obtain a clean cutting edge. Nevertheless, this solution takes longer than manual cutting using the cutter. Furthermore, the plasterboard sheets of small thickness (less than or equal to 18 millimeters) are unsuited to the use of a saw. This solution becomes advantageous only for thicknesses greater than 20 millimeters because, beyond this thickness, the strain to be exerted to break the layer of plaster is too great and the break does not necessarily follow the score.
The aim of the present invention is therefore to propose a rapid and clean solution for cutting a plasterboard sheet.